Provisioning composite applications using secure parameter access

ABSTRACT

A mechanism for provisioning a composite web application using secure parameter transfer is disclosed. The composite web application includes a component that resides on a virtual machine (VM). A request is received from the component for a configuration parameter that is to enable periodic reconfiguration of the VM. An access condition is identified for accessing the configuration parameter and responsive to determining the access condition is satisfied, the requested configuration parameter is provided to the component. The VM is reconfigured using the requested configuration parameter.

PRIORITY CLAIM TO RELATED APPLICATION

This application is a continuation of and claims the benefit under 35U.S.C. § 120 of U.S. patent application Ser. No. 13/484,194, filed onMay 30, 2012, entitled “Provisioning Composite Applications Using SecureParameter Access,” the entirety of which is incorporated herein byreference.

TECHNICAL FIELD

The embodiments of the invention relate generally to softwareprovisioning and, more specifically, relate to a mechanism forprovisioning a composite application.

BACKGROUND

Software provisioning is the process of loading the appropriate software(such as operating system, device drivers, middleware, and applications)on a target machine, and customizing and configuring the system and thesoftware to make it ready for operation. Software provisioning canentail a variety of tasks, such as creating or changing a boot image,and specifying parameters such as IP address, IP gateway, and networkconnections. The machine being provisioned can be a physical machine ora virtual machine executing on a host.

A composite application is an application that is installed on multiplemachines. Usually the composite application is installed on multiplevirtual machines, where each component of the application is installedon a virtual machine optimized for the component. The compositeapplication and its components are made up of several software“applications,” so the composite application will sometimes be referredto as a composite service.

For example, a composite application or service can be a Webapplication, such as a social networking site, or a blog site. Such acomposite application can have various components. For example, a 3-tierapplication will have an interface tier (Web server), a business logictier (application server) and a data tier (database management system).Various other tiers are possible, including an orchestration tier todistribute and manage jobs between multiple servers and a load balancingtier to distribute load between clients and the interface tier. Thenumbers of each of the components of a composite application canincrease and decrease dynamically based on demand, making it difficultto manually provision and configure components of a distributedcomposite application.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be understood more fully from thedetailed description given below and from the accompanying drawings ofvarious embodiments of the invention. The drawings, however, should notbe taken to limit the invention to the specific embodiments, but are forexplanation and understanding only.

FIG. 1 is a block diagram of a network environment for implementing aprovisioning server according to one embodiment of the presentinvention.

FIG. 2 is a block diagram of a composite application provisioned using aprovisioning server according to one embodiment of the presentinvention.

FIG. 3 is a block diagram illustrating data structures used by aprovisioning server according to one embodiment of the presentinvention.

FIG. 4 is a block diagram illustrating a hierarchical data structure forstoring configuration parameter values according to one embodiment ofthe present invention.

FIG. 5 is a block diagram illustrating a hierarchical data structure forstoring maximum memory configuration parameter values according to oneembodiment of the present invention.

FIG. 6 is a block diagram illustrating a hierarchical data structure forstoring failover scheme configuration parameter values according to oneembodiment of the present invention.

FIG. 7 is a block diagram illustrating a hierarchical data structure forstoring connection pooling configuration parameter values according toone embodiment of the present invention.

FIG. 8 is a block diagram illustrating a hierarchical data structure forstoring database password configuration parameter values according toone embodiment of the present invention.

FIG. 9 is a flow diagram illustrating virtual machine provisioningaccording to one embodiment of the present invention.

FIG. 10 is a flow diagram illustrating using a hierarchical datastructure for virtual machine provisioning according to one embodimentof the present invention; and

FIG. 11 illustrates a block diagram of one embodiment of a computersystem.

DETAILED DESCRIPTION

Embodiments of the invention provide a mechanism for provisioningcomposite application using secure parameter access. A method ofembodiments of the invention includes receiving a request for aconfiguration parameter from a first component of a composite Webapplication residing on a first virtual machine (VM). The requestedconfiguration parameter can be related to a second component of thecomposite Web application residing on a second VM. The role of the firstcomponent in the composite Web application is identified and adetermination is made as to whether the first component has access tothe requested configuration parameter based on the role of the firstcomponent. If the first component has access, then the requestedconfiguration parameter is provided to the first component.

In the following description, numerous details are set forth. It will beapparent, however, to one skilled in the art, that the present inventionmay be practiced without these specific details. In some instances,well-known structures and devices are shown in block diagram form,rather than in detail, in order to avoid obscuring the presentinvention.

Some portions of the detailed descriptions which follow are presented interms of algorithms and symbolic representations of operations on databits within a computer memory. These algorithmic descriptions andrepresentations are the means used by those skilled in the dataprocessing arts to most effectively convey the substance of their workto others skilled in the art. An algorithm is here, and generally,conceived to be a self-consistent sequence of steps leading to a desiredresult. The steps are those requiring physical manipulations of physicalquantities. Usually, though not necessarily, these quantities take theform of electrical or magnetic signals capable of being stored,transferred, combined, compared, and otherwise manipulated. It hasproven convenient at times, principally for reasons of common usage, torefer to these signals as bits, values, elements, symbols, characters,terms, numbers, or the like.

It should be borne in mind, however, that all of these and similar termsare to be associated with the appropriate physical quantities and aremerely convenient labels applied to these quantities. Unlessspecifically stated otherwise, as apparent from the followingdiscussion, it is appreciated that throughout the description,discussions utilizing terms such as “sending”, “receiving”, “attaching”,“forwarding”, “caching”, “comparing,” “matching,” or the like, refer tothe action and processes of a computer system, or similar electroniccomputing device, that manipulates and transforms data represented asphysical (electronic) quantities within the computer system's registersand memories into other data similarly represented as physicalquantities within the computer system memories or registers or othersuch information storage, transmission or display devices.

The present invention also relates to an apparatus for performing theoperations herein. This apparatus may be specially constructed for therequired purposes, or it may comprise a general purpose computerselectively activated or reconfigured by a computer program stored inthe computer. Such a computer program may be stored in a machinereadable storage medium, such as, but not limited to, any type of diskincluding floppy disks, optical disks, CD-ROMs, and magnetic-opticaldisks, read-only memories (ROMs), random access memories (RAMs), EPROMs,EEPROMs, magnetic or optical cards, or any type of media suitable forstoring electronic instructions, each coupled to a computer system bus.

The algorithms and displays presented herein are not inherently relatedto any particular computer or other apparatus. Various general purposesystems may be used with programs in accordance with the teachingsherein, or it may prove convenient to construct more specializedapparatus to perform the required method steps. The required structurefor a variety of these systems will appear as set forth in thedescription below. In addition, the present invention is not describedwith reference to any particular programming language. It will beappreciated that a variety of programming languages may be used toimplement the teachings of the invention as described herein.

The present invention may be provided as a computer program product, orsoftware, that may include a machine-readable medium having storedthereon instructions, which may be used to program a computer system (orother electronic devices) to perform a process according to the presentinvention. A machine-readable medium includes any mechanism for storingor transmitting information in a form readable by a machine (e.g., acomputer). For example, a machine-readable (e.g., computer-readable)medium includes a machine (e.g., a computer) readable storage medium(e.g., read only memory (“ROM”), random access memory (“RAM”), magneticdisk storage media, optical storage media, flash memory devices, etc.),etc.

FIG. 1 is a block diagram of a network architecture 100 in whichembodiments of the invention may operate. The network architecture 100includes a cloud 130 managed by a cloud provider system 104. The cloud130 provides virtual machines, such as virtual machines 111, 112, 121,and 122. Each virtual machine is hosted on a physical machine configuredas part of the cloud 130. Such physical machines are often located in adata center. For example, virtual machines 111 and 112 are hosted onphysical machine 110 in cloud 130 provided by cloud provider 104. Userscan interact with applications executing on cloud-based virtual machinesusing client computer systems, such as clients 160, 170 and 180, viacorresponding web browser programs 161, 171 and 181. Clients 160, 170and 180 may be associated with one or more organizations other than thatmaintaining the cloud 130.

Clients 160, 170 and 180 are connected to hosts 110, 120 and the cloudprovider system 104 via a network 102, which may be may be a privatenetwork (e.g., a local area network (LAN), a wide area network (WAN),intranet, or other similar private networks) or a public network (e.g.,the Internet). Each client 160, 170, 180 may be a mobile device, a PDA,a laptop, a desktop computer, or any other computing device. Each host110, 120 may be a server computer system, a desktop computer or anyother computing device. The cloud provider system 104 may include one ormore machines such as server computers, desktop computers, etc.

In one embodiment, the network architecture includes a provisioningserver 135 to configure components of composite applications. Acomposite application is a single service (such as a blog) that isimplemented by several separate components being provided by multiplevirtual machines. For example, component 150 residing on VM 112 andcomponent 155 residing on VM 121 can be separate components of a singlecomposite application. In one embodiment, the provisioning server 135stores configuration parameters to configure the components of thecomposite application in one or more hierarchical data stores 140. Theprovisioning server 135 may be hosted by the same machine(s) as thecloud provider system 104 or one or more other machines such as servercomputers, desktop computers, etc.

While various embodiments are described in terms of the environmentdescribed above, the facility may be implemented in a variety of otherenvironments including a single, monolithic computer system, as well asvarious other combinations of computer systems or similar devicesconnected in various ways.

FIG. 2 is a block diagram illustrating a computing environment 200according to an embodiment of the invention. The computing environmentincludes a cloud 205 implemented by a cloud provider that caninstantiate virtual machines that can be used to execute application andcomponents of composite applications. As an example, the virtualmachines used to implement one such composite application are shown inFIG. 2. The composite application may be a multi-tier application (e.g.,three tier application) and the components may include Web servers,application servers, and database management systems. In the exampleshown in FIG. 2, the composite application has two Web server components210 a, b, three application server components 215 a-c, and one databasemanagement system 220. In one embodiment, each of these components isimplemented on a separate virtual machine, although they may or may notbe hosted on the same physical host machine.

The composite application can be accessed by users, for example, viaclient machines 255 a-c that can access the cloud 205 via a network 250,such as the Internet. In a usual Web application, the client 255 wouldinteract with a Web server 210 using a protocol such as HTTP/S, and theWeb server 210 would service the requests of the client 255 byinteracting with an application server 215, which may in turn interactwith a database management system 220.

The components of the composite application may change to demand, byrequest from the application owner, changes in the network, or forseveral other reasons. For example, if the third application server 215c is added due to increased load on the first two application servers215 a, b, then the third application server 215 c needs to be configuredto operate as part of the composite application. In one embodiment, theapplication server 215 c would be brought online by the cloud provideras a pre-configured application server. However, after being booted up,the new application server 215 c will still need to be configured tooperate as part of the composite application.

A new component being added to the composite application—or a componentrequesting a periodic reconfiguration or update—may need severalconfiguration parameters to operate as part of the compositeapplication. For example, an application server may need to know itsassigned databases, the database passwords, connection pooling and otherresource pooling settings, failover settings, security settings, amongother configuration settings and parameters.

In one embodiment, a component being configured can request itsconfiguration parameters from a provisioning server 230. Theprovisioning server 230 maintains a configuration data store 235 thatcontains the values and rules for determining and calculating theappropriate values for configuration parameters. In one embodiment, theprovisioning server 230 accesses an application data store 240 and aconfiguration data store 235 to provide requested configurationinformation. The application data store 240 and a configuration datastore 235 can reside on one physical storage device, separate storagedevices, network storage, or any other storage mechanism.

FIG. 3 illustrates two example data structures that can be stored in oneembodiment in the application data store 240. Embodiments of such datastructures are used by the provisioning server 230 to maintaininformation about the composite Web applications being provisioned bythe provisioning server 230. In one embodiment, the application datastore can include a virtual machine (VM) table.

One embodiment of a VM table is illustrated with reference to FIG. 3.The VM table 305 includes entries or records that each represent one ofthe VMs provisioned by the provisioning server 230. In one embodiment, arecord includes a component identifier (CID) or the component of adistributed Web application being provided by the VM, a VMidentifier—such as the hostname of the VM—an Application identifier—suchas the name of the distributed application—such as “Bob's Food Blog”—anapplication type identifier—such as “Blog”—a role of the component—suchas “database”—and various configuration data that indicated the presentconfiguration of the VM referenced by the record.

In one embodiment, the application data store 240 also includes anapplication table 310. The application table contains recordscorresponding with composite Web applications that are provisioned bythe provisioning server 230. In one embodiment, each record includes anapplication identifier, an application name, an application type, and alist of all the individual components that make up the composite Webapplication.

With reference again to FIG. 2, configuration values and rules arestored, in one embodiment, in configuration data store 235 that isaccessible by the provisioning server 230. For example, if there is anew application server 215 c being introduced into the composite Webapplication to handle increased load, then the application server 215 ccan query the provisioning server 230 for configuration information. Inone embodiment, some configuration parameters being requested from theprovisioning server depend on the relationship between the requestingcomponent—such as application server 215 c—and some or all of the othercomponents of the composite Web application. Furthermore, somecomponents only have access to certain configuration parameters if theyhave the right relationship with some or all of the other components ofthe composite Web application.

In one embodiment, the provisioning server manages the configurationparameter and accesses dependencies of the composite Web applicationusing a hierarchical data structure. An example of a hierarchical datastructure is provided in FIG. 4. In the embodiment shown, thehierarchical data structure 400 is logically organized in levels (L2,L1, L0). Each level has one or more elements 405. Each element includesa match condition and a parameter value, or a formula to calculate aparameter value. Each configuration parameter has an associatedhierarchical data structure 400. Thus, the requested configurationparameter 410 is the key into the hierarchical data structure 400.

In one embodiment, the match condition represents the condition therequesting component should satisfy to access and be provided theparameter value in the element 405. In one embodiment, the matchconditions of elements 405 of the same level of hierarchy use the sameinformation about the requesting component. In one embodiment, thelevels are checked for a match starting with the highest level andending with the default (L0) level if no other matches are found

In one embodiment, the hierarchical data structure 400 also has anaccess condition 415 that should be satisfied by the requestingcomponent before access to the elements 405 is granted. In otherembodiment, the access condition 415 can be incorporated into everymatch condition, including the default condition, of each element 405 ofthe hierarchical data structure. Various examples illustrating thehierarchical data structure are provided below with reference to FIGS.5-8.

FIG. 5 is a block diagram illustrating a hierarchical data structure 500that stores configuration parameters and formulas for the configurationparameter of maximum memory. When a new server is being provisioned as anetwork (cloud) based virtual machine, one configuration parameter to bedetermined is how much physical memory the virtual machine will beallowed to access. Thus, when a new server is created to instantiate acomponent of the composite Web application, the new component canrequest the configuration parameter of maximum memory from theprovisioning server.

The provisioning server can then access the configuration data store andlocate the hierarchical data structure 500 using the maximum memoryparameter as the key 505. In one embodiment, before matching the elementof the hierarchical data structure 500 containing the appropriateconfiguration parameter value, the access condition 510 is evaluated todetermine whether the requesting component has access to the requestedvalue. In the example of FIG. 5, the access condition is that the roleof the requesting component is an application server of the compositeWeb application.

Thus, if the requesting component is a Web server, in this example, thenit would not be provided the requested configuration parameter. Thus,when a request is received, in one embodiment, the component identifierof the requesting component is used to look up the role of the componentin the VM table or similar data structure. If the access conditionrequires other information about the component, then such information isretrieved from the VM table, the application table, or other similardata structures.

If the access condition is satisfied, in this example, the role of therequesting component is indeed that of application server, and then theinformation about the component for checking the match conditions on thehighest level of the hierarchical data structure 500. In the example ofFIG. 5, the highest level of the hierarchical data structure 500 islevel two, and there is one element 520 on level two.

The information about the component for checking the level two matchconditions may be the application type. Thus, the application type ofthe composite Web application that component will be part of can belooked up in the VM table or similar data structure. The match conditionin element 520 is that the application type is blog. Thus, if therequesting application server—in this example—is part of a blogcomposite application, then the match condition of element 520 issatisfied, and the value contained in element 520 (500 Mb) is providedas the maximum memory for the component. In this manner, informationabout the composite application in general is used to determine aconfiguration parameter of a component of the composite application.

If the match condition of element 520 is not satisfied, then, sincethere are no other elements on level two, the next level of thehierarchical data structure is accessed. Level one also has one element530. The information about the component needed to check the level onematch conditions is the number of Web server components of the compositeapplication. Thus, in this example, the composite Web application thatcomponent will be part of is looked up in the VM table or similar datastructure, and then the number of Web servers of the application will belooked up in the application table, or similar data structure.

The match condition in element 530 may be that the composite applicationthe requesting component is part of has three or more Web servers. Thus,if the requesting application server—in this example—has five Webservers, then the match condition of element 530 is satisfied. Insteadof a simple constant value, element 530 contains a formula forcalculating the value for the requested configuration parameter.

In this example, the formula in element 530 states that the value forthe maximum memory is 1 Gb times the number or Web servers. Thus, inthis example, five Web servers would result in a value of 5 Gb returnedfor the requested maximum memory configuration parameter. In thismanner, information about other components of the composite applicationcan be used to determine a configuration parameter for a requestingcomponent of the composite application.

However, if the composite Web application has, for example, two Webservers, then the match condition of element 530 would not be satisfied.Since there are no additional elements on level one of the hierarchicaldata structure 500, level zero is accessed. Level zero is the defaultlevel. In one embodiment, the default level has one element 540 and nomatch condition. When level zero is accessed, the value on the defaultelement—in this example 1 Gb—is returned as the requested maximum memoryvalue.

FIG. 6 is another example of looking up and determining a configurationparameter being requested by a composite application in a hierarchicaldata structure. FIG. 6 is a block diagram illustrating a hierarchicaldata structure 600 that stores configuration parameters and formulas forthe configuration parameter of failover scheme. As discussed above, thekey 605 into the hierarchical data structure 600 is failover scheme, andthe access condition 610 is once again that the requesting component beassigned the role of application server in the composite application.

Since level 1 is the highest level in this example, this level is thefirst to be accessed. The information about the component needed tocheck the level one match conditions is the number of applicationservers in the composite application after the inclusion of theapplication server being provisioned. Thus, the VM table and theapplication table are accessed to determine the number of applicationservers already operating in the composite application.

The match condition of element 620 is that the number of applicationservers in the composite application is one, meaning that theapplication server being provisioned is the first application server ofthe composite application. In this case, the value for the failoverconfiguration parameter is to “restart on failure.” If the compositeapplication is found to already have three application servers, then thematch condition of element 620 is not satisfied, but the match conditionof element 625 of level one would be. The match condition of elements620 and 625 both require the same information about the compositeapplication or its components to evaluate, since they are both on level1.

Thus, the composite application having three application servers wouldsatisfy the match condition of element 625, which requires that thecomposite application have less than eight application servers. In sucha situation, an active/active node configuration can be used toimplement a high availability failover cluster, and the valueactive/active is returned as the failover scheme to use for the newapplication server being provisioned. (In an active/active clustertraffic intended for a failed node is passed to another node or loadbalanced to all or several remaining nodes.) Since the provisioningserver is also aware of the other application servers, the clusteringcan be automatically configured in the new application server.Furthermore, in one embodiment, the configuration information of thosecomponents can be automatically updated to reflect the addition of thenew application server to the active-active cluster.

If the composite application has more than eight application servers,then the default level is accessed, and the default value is applied. Inthis example, the default rule is that size eight active-active clustersare created. Thus, if the number of application servers modulo eight iszero, then a new failover cluster is started for the new applicationserver. Otherwise, the new application server is added to the failovercluster than has fewer than eight members.

FIG. 7 is another example of looking up and determining a configurationparameter being requested by a composite application in a hierarchicaldata structure. FIG. 7 is a block diagram illustrating a hierarchicaldata structure 700 that stores configuration parameters and formulas forthe configuration parameter of connection pooling. Other resourcepooling configuration parameters can be implemented in a substantiallysimilar manner. The operation of, and accesses to, the hierarchical datastructure 700 is similar to that described with reference to FIGS. 5 and6, and will not be discussed in as much detail.

The hierarchical data structure 700 also illustrates that compoundconditions can be used for the match conditions of elements, and alsofor the access rule (although that is not the case in FIG. 7). Element720 implements the highest level rule, that if the host physical machineof the requesting application server is the same as the host physicalmachine of the database to be connected to the requesting applicationserver (i.e., the two components are hosted on the same physicalmachine), then interprocess communication should be used for connectionpooling.

At level one, element 730 has a compound match condition. In thisexample, the match condition is satisfied if both the number ordatabases and the number of application servers of the compositeapplication are one. Thus, these two pieces of information are firstretrieved, and then compared with the level one match conditions inelement 730, and in element 735 if the match condition of element 730 isnot satisfied. Similarly, the match condition of element 735 issatisfied if the composite application has one database, but more thanone application servers. If none of the level one elements apply, thenthe default value of element 740 of level zero is returned as theconnection pooling configuration parameter.

FIG. 8 is another example of looking up and determining a configurationparameter being requested by a composite application in a hierarchicaldata structure. FIG. 8 is a block diagram illustrating a hierarchicaldata structure 800 that stores configuration parameters and formulas forthe configuration parameter of database password. In this example, whena new application server is added to the composite application, it needsto know the passwords of the databases to which it is connected. Theoperation of and accesses to the hierarchical data structure 800 issimilar to that described with reference to FIGS. 5 and 6, and will notbe discussed in as much detail.

The database password example illustrated, among other things, that theaccess condition 810 can be a compound condition as well. In thisexample, a component is allowed access to database passwords if its rolein the composite application is that of application server, and thedatabases whose passwords are requested are components of the sameapplication.

In another embodiment, this access condition can be built into the matchstatements of elements 820 and 825. For example, in addition torequiring that the requested database connection be DB1 (a database),the match condition can include the condition that DB1 be part of thesame composite application as the requesting application server. Element825 can include a similar compound condition for DB2 in its matchcondition. In this manner, access can be restricted to both an entirehierarchical data structure 800—using an access condition—and on anelement-by-element basis—using compound match conditions for elements tocontrol access in addition to matching values for configurationparameter requests.

FIGS. 4-8 only illustrate a few examples of using a hierarchical datastructure to store configuration parameter values and to control accessto those values. Each of the examples above assumed that an applicationserver was being provisioned, but similar techniques can be used toprovision any type of component for a composite application. As theseexamples demonstrate, by having an entity independent of the compositeapplication, but aware of the components of the composite applicationand their roles in the composite application, store the values and rulesfor configuration parameters, access to such configuration parameterscan be controlled based on the roles of the various components beingprovisioned. Furthermore, more complex, more component-aware, and moreapplication-aware configuration parameter rules can be created when itis possible to use information about other components of a compositeapplication during provisioning of a new or existing component of thecomposite application.

FIG. 9 is a flow diagram illustrating a method 900 for servicing arequest for a configuration parameter from a component of a compositeapplication according to an embodiment of the invention. Method 900 maybe performed by processing logic that may comprise hardware (e.g.,circuitry, dedicated logic, programmable logic, microcode, etc.),software (such as instructions run on a processing device), firmware, ora combination thereof. In one embodiment, method 900 is performed byprovisioning server 230 of FIG. 2.

Method 900 begins at block 910 where a request is received by an entity,such as the provisioning server, that is aware of all components of acomposite application. In one embodiment, the composite application isbeing implemented using multiple virtual machines in a cloud-based Webapplication hosting environment, where the owner of the compositeapplication can select the different components of the compositeapplication the owner wants to implement. The request is from one suchvirtual machine that is being configured upon creation or as part ofongoing periodic reconfiguration.

In one embodiment, the received request is a request for, or includes arequest for, a specific configuration parameter. For example, theconfiguration parameter can be a database password for a databasemanagement system component. The requested configuration parameter, inone embodiment, is related to another component of the compositeapplication, as with the database password example.

At block 920, the component of the composite application implemented inthe virtual machine from which the request was received is identified.This can be done, for example, by looking up an identifier of thevirtual machine that sent the request for the configuration parameter ina table or database that associates composite application componentswith virtual machines. In one embodiment, each virtual machineimplements one component of the composite application. In other words,in such an embodiment, each component is implemented using a separatevirtual machine. For example, if a second Web server is desired inaddition to a current Web server, a new virtual machine implementing thenew Web server is created and provisioned.

At block 930 the role of the component is identified. Generally, Webapplications have some established roles for servers, such as Webserver, application server, database server, mobile app server,orchestration server, ad server, load balancing server, etc. However,other applications or Web applications can divide roles differently oraccording to a non-traditional scheme.

At block 940, an attempt is made to match an access condition thatshould be satisfied to access the requested configuration parameter. Forexample, if database servers only connect to application servers, thenthe access condition to a database password may be that the role of therequesting component be application server. In another embodiment, theaccess condition is specific not only to the role of the requestingcomponent but to the relationship of the requesting component to thecomponent that is related to the requested configuration parameter.

For example, in the case of a database password, the access conditioncan be that the requesting component have the role of applicationserver, and that the requesting application server be connected to thedatabase whose password is requested. One example of a hierarchical datastructure to implement such an access condition is described withreference to FIG. 8 above.

At block 950, a determination is made as to whether permission to havethe requested configuration parameter is granted. If permission isdenied, processing terminates. In one embodiment, if the requestedconfiguration parameter is needed to provision the requesting component,then an error message may be generated or an alternate configurationparameter may be used or attempted.

If, however, access to the requested configuration parameter is granted,then, at block 960, the value of the requested configuration parameteris retrieved. In one embodiment, this is done by locating theappropriate value by traversing levels of match conditions of ahierarchical data structure. In other embodiment, the requested valuecan be looked up in a table, a database, a tree structure, or some otherdata structure. At block 970 the value for the requested configurationparameter is provided to the virtual machine from which the request wasreceived in block 910, and processing terminates. When a new virtualmachine is being provisioned, many configuration parameters can berequested and provided simultaneously or in parallel.

FIG. 10 is a flow diagram illustrating a method 1000 for looking up avalue for a configuration parameter for a component of a compositeapplication according to an embodiment of the invention. Method 1000 maybe performed by processing logic that may comprise hardware (e.g.,circuitry, dedicated logic, programmable logic, microcode, etc.),software (such as instructions run on a processing device), firmware, ora combination thereof. In one embodiment, method 1000 is performed byprovisioning server 230 of FIG. 2.

Method 1000 begins at block 1010 where a request for a configurationparameter is received from a component of a composite application. Atblock 1020, the hierarchical data structure associated with therequested configuration parameter is accessed. In one embodiment, therequested configuration parameter is used as a key to locate theappropriate hierarchical data structure from a group of hierarchicaldata structures stored in a configuration data store.

At block 1030, the next appropriate level of the hierarchical datastructure is selected and information about the composite applicationassociated with the selected level is retrieved. When the hierarchicaldata structure is first accessed in response to the received request,the highest level is the first level accessed. The information about thecomposite application retrieved is the information used to check matchconditions of elements of the selected level of the hierarchical datastructure, such as the type of the composite application, the number ofcomponents, the number of databases, or whatever information is checkedby the match conditions of the selected level.

In one embodiment, the information about the composite applicationrelates to components other than the requesting component. In yet otherembodiments, the information about the composite application alsoinclude relationships between the requesting component and one or moreother components of the composite application, such as how manyapplication servers are connected to a requesting database server.

At block 1040, attempts are made to match the match conditions of theelements of the selected level of the hierarchical data structure usingthe retrieved information about the composite application. At block1050, a determination is made as to whether any of the match conditionsof the elements of the selected level of the hierarchical data structurehave been satisfied. If the match condition of one of the elements ofthe selected level of the hierarchical data structure is satisfied,then, in block 1060, the value from the element whose match condition issatisfied is returned as the requested configuration parameter value tothe requesting component of the composite application.

However, if none of the match conditions of the elements of the selectedlevel of the hierarchical data structure are satisfied, then processingcontinues at block 1030 with the selection of the new level of thehierarchical data structure and the retrieving of the information aboutthe composite application needed to check the match conditions of theone or more elements of this next selected level. In one embodiment, theprocessing is guaranteed to terminate by the use of a default element onthe lowest level of the hierarchical data structure, as explainedfurther above.

FIG. 11 illustrates a diagrammatic representation of a machine in theexemplary form of a computer system 1100 within which a set ofinstructions, for causing the machine to perform any one or more of themethodologies discussed herein, may be executed. In alternativeembodiments, the machine may be connected (e.g., networked) to othermachines in a LAN, an intranet, an extranet, or the Internet. Themachine may operate in the capacity of a server or a client machine in aclient-server network environment, or as a peer machine in apeer-to-peer (or distributed) network environment. The machine may be apersonal computer (PC), a tablet PC, a set-top box (STB), a PersonalDigital Assistant (PDA), a cellular telephone, a web appliance, aserver, a network router, switch or bridge, or any machine capable ofexecuting a set of instructions (sequential or otherwise) that specifyactions to be taken by that machine. Further, while only a singlemachine is illustrated, the term “machine” shall also be taken toinclude any collection of machines that individually or jointly executea set (or multiple sets) of instructions to perform any one or more ofthe methodologies discussed herein.

The exemplary computer system 1100 includes a processing device 1102, amain memory 1104 (e.g., read-only memory (ROM), flash memory, dynamicrandom access memory (DRAM) (such as synchronous DRAM (SDRAM) or DRAM(RDRAM), etc.), a static memory 1106 (e.g., flash memory, static randomaccess memory (SRAM), etc.), and a data storage device 1118, whichcommunicate with each other via a bus 1130.

Processing device 1102 represents one or more general-purpose processingdevices such as a microprocessor, central processing unit, or the like.More particularly, the processing device may be complex instruction setcomputing (CISC) microprocessor, reduced instruction set computer (RISC)microprocessor, very long instruction word (VLIW) microprocessor, orprocessor implementing other instruction sets, or processorsimplementing a combination of instruction sets. Processing device 1102may also be one or more special-purpose processing devices such as anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA), a digital signal processor (DSP), network processor,or the like. The processing device 1102 is configured to execute theinstructions 1122 for performing the operations and steps discussedherein.

The computer system 1100 may further include a network interface device1108. The computer system 1100 also may include a video display unit1110 (e.g., a liquid crystal display (LCD) or a cathode ray tube (CRT)),an alphanumeric input device 1112 (e.g., a keyboard), a cursor controldevice 1114 (e.g., a mouse), and a signal generation device 1116 (e.g.,a speaker).

The data storage device 1118 may include a machine-accessible storagemedium 1128 on which is stored instructions 1122 embodying any one ormore of the methodologies of functions described herein. For example,instructions 1122 may be instructions to perform component provisioningdescribed with respect to FIG. 9. The instructions 1122 may also reside,completely or at least partially, within the main memory 1104 and/orwithin the processing device 1102 during execution thereof by thecomputer system 1100; the main memory 1104 and the processing device1102 also constituting machine-accessible storage media.

The machine-readable storage medium 1128 may also be used to storeinstructions to perform component provisioning described with respect toFIG. 9, and/or a software library containing methods that call the aboveapplications. While the machine-accessible storage medium 1128 is shownin an exemplary embodiment to be a single medium, the term“machine-accessible storage medium” should be taken to include a singlemedium or multiple media (e.g., a centralized or distributed database,and/or associated caches and servers) that store the one or more sets ofinstructions. The term “machine-accessible storage medium” shall also betaken to include any medium that is capable of storing, encoding orcarrying a set of instruction for execution by the machine and thatcause the machine to perform any one or more of the methodologies of thepresent invention. The term “machine-accessible storage medium” shallaccordingly be taken to include, but not be limited to, solid-statememories, and optical and magnetic media.

Whereas many alterations and modifications of the present invention willno doubt become apparent to a person of ordinary skill in the art afterhaving read the foregoing description, it is to be understood that anyparticular embodiment shown and described by way of illustration is inno way intended to be considered limiting. Therefore, references todetails of various embodiments are not intended to limit the scope ofthe claims, which in themselves recite only those features regarded asthe invention.

What is claimed is:
 1. A method comprising: implementing a composite webapplication, wherein the composite web application comprises a firstcomponent that resides on a first virtual machine (VM); receiving, fromthe first component, a request for a configuration parameter, whereinthe configuration parameter is to enable periodic reconfiguration of thefirst VM; identifying, using a hierarchical data structure, an accesscondition for accessing the configuration parameter; responsive todetermining that the access condition is satisfied by the firstcomponent in view of a role of the first component, providing therequested configuration parameter to the first component; andreconfiguring the first VM using the requested configuration parameter.2. The method of claim 1, further comprising: responsive to determiningthat the access condition is not satisfied by the first component inview of the role of the first component, denying access to the requestedconfiguration parameter by the first component.
 3. The method of claim1, wherein the composite web application further comprises a secondcomponent that resides on a second VM.
 4. The method of claim 3, whereinreconfiguring the first VM using the requested configuration parameterenables communication between the first component and the secondcomponent.
 5. The method of claim 3, wherein the first VM and the secondVM are VMs of a cloud-based Web application hosting environment.
 6. Themethod of claim 1, further comprising: identifying, from the accesscondition, a requirement for an attribute of the first component; andidentifying the attribute of the first component.
 7. The method of claim6, wherein determining whether the first component has access to therequested configuration parameter comprises comparing the attribute to amatch condition of at least one element of the hierarchical datastructure.
 8. The method of claim 7, further comprising, responsive todetermining that the attribute does not satisfy any match condition ofany element of the hierarchical data structure, providing a defaultconfiguration parameter to the first component.
 9. A system comprising:a memory, and a processor coupled to the memory to perform: implementinga composite web application, wherein the composite web applicationcomprises a first component that resides on a first virtual machine(VM); receiving, from the first component, a request for a configurationparameter, wherein the configuration parameter is to enable periodicreconfiguration of the first VM; identifying, using a hierarchical datastructure, an access condition for accessing the configurationparameter; responsive to determining that the access condition issatisfied by the first component in view of a role of the firstcomponent, providing the configuration parameter to the first component;and reconfiguring the first VM using the requested configurationparameter.
 10. The system of claim 9, wherein the processor is furtherto perform: responsive to determining that the access condition is notsatisfied in view of the role of the first component, denying access tothe requested configuration parameter by the first component.
 11. Thesystem of claim 9, wherein the composite web application furthercomprises a second component that resides on a second VM.
 12. The systemof claim 11, wherein reconfiguring the first VM using the requestedconfiguration parameter enables communication between the firstcomponent and the second component.
 13. The system of claim 11, whereinthe first VM and the second VM are VMs of a cloud-based Web applicationhosting environment.
 14. The system of claim 9, wherein the processor isfurther to perform: identifying, from the access condition, arequirement for an attribute of the first component; and identifying theattribute of the first component.
 15. The system of claim 14, whereindetermining whether the first component has access to the requestedparameter comprises comparing the attribute to a match condition of atleast one element of the hierarchical data structure.
 16. The system ofclaim 15, wherein the processor is further to perform, responsive todetermining that the attribute does not satisfy any match condition ofany element of the hierarchical data structure, providing a defaultconfiguration parameter to the first component.
 17. A non-transitorycomputer-readable storage medium programmed to include instructionsthat, when executed by a processing device, cause the processing deviceto perform a method comprising: implementing, by a provisioning server,a composite web application, wherein the composite web applicationcomprises a first component that resides on a first virtual machine(VM); receiving, from the first component, a request for a configurationparameter, wherein the configuration parameter is to enable periodicreconfiguration of the first VM; identifying, using a hierarchical datastructure, an access condition for accessing the configurationparameter; responsive to determining that the access condition issatisfied by the first component in view of a role, providing theconfiguration parameter to the first component; and reconfiguring thefirst VM using the requested configuration parameter.
 18. Thenon-transitory computer-readable storage medium of claim 17, wherein thecomposite web application further comprises a second component thatresides on a second VM, and wherein reconfiguring the first VM using therequested configuration parameter enables communication between thefirst component and the second component.
 19. The non-transitorycomputer-readable storage medium of claim 17, wherein the processingdevice is further to: identify, from the access condition, a requirementfor an attribute of the first component; and identify the attribute ofthe first component.
 20. The non-transitory computer-readable storagemedium of claim 19, wherein determining whether the first component hasaccess to the requested configuration parameter comprises comparing theattribute to a match condition of at least one element of thehierarchical data structure.